electric mirrors

[Mark Zvolanek <mzvolane@sydney.ipex.com.au>]

G'day Audi collective wisdom.
This morning (hot day 30C+) electric mirror fuse 5A blew.
This is on RHD 1991 90.
After analysis I found out that, if I replace the fuse and
When I flick the mirror selector switch to LHS mirror the LHS mirror   
motor is continuously on trying to move the mirror down.
When I flick the mirror selector switch to neutral position the motor on   
LHS mirror stops.
When I flick the mirror selector switch to RHS mirror the RHS mirror   
motor is not continuously on, ie it works fine.
This makes me believe that problem is not caused by the round switch in   
the drivers door that is used to adjust mirrors.
Does my logic sound OK ?
Did anyone have similar problem?
What would be your recommendation on troubleshooting this problem?
Thanks to you all.
Mark Zvolanek